FLU BASICS: What Is the Flu?, Who Is at Risk?, Signs and Symptoms of Flu, and Flu Past…and Future

What Is the Flu?

Influenza—often called the flu—is a contagious, potentially serious respiratory illness caused by influenza viruses that attack the upper respiratory tract. It can cause mild to severe illness and at times can lead to death. Flu viruses are easily spread from person to person in respiratory droplets released into the air by coughing and sneezing.

It's also possible (though uncommon) to become infected by touching an object that has viruses on it, like a telephone or doorknob, and then touching your nose or mouth.

Effects of Flu

The flu can make people of all ages seriously ill. Symptoms include high fever, extreme tiredness, headache, dry cough, sore throat, muscle aches, and more. (Children may also experience nausea, diarrhea and vomiting.) Flu may lead to bronchitis and pneumonia, or asthma, diabetes, lung and heart problems, such as chronic obstructive pulmonary disease (COPD) and congestive heart failure.

Flu causes about 200,000 hospitalizations and 36,000 deaths each year in the U.S. Depending upon which flu virus strains are circulating, the disease sickens from five percent to 20 percent of the people in the U.S. annually during the fall and winter flu "season." The viruses may be active from October to May.

Help Avoid the Flu

According to the U.S. Centers for Disease Control and Prevention (CDC) and its Advisory Committee on Immunization Practices (ACIP), the best way to prevent flu and protect yourself and others from serious complications is to get an annual flu vaccination.

Two types of vaccines are available in the U.S. One is inactivated (killed) and given as an injection; the other is a live attenuated (weakened) nasal-spray vaccine. Protection develops two weeks after vaccination. Both types reduce flu risk, but the nasal spray is only approved for healthy people, ages five to 49, with no chronic conditions or other risks (including pregnancy).

A word of caution: If you are allergic to eggs, have ever had an allergic reaction to flu vaccine, have ever had Guillain-Barré Syndrome, or have a current illness, consult your health care professional before receiving either vaccine.

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Who Is at Risk?

Anyone can get the flu. The virus is contagious and may spread from person to person before symptoms appear and up to five days afterwards. Children may be infectious for 10 days or more. Smoking increases your risk of flu infection and the illness can be more severe because of it.

Because flu thrives in close quarters, such as schools, children are more likely to become infected than adults. Yet older people and very young children are more likely to be hospitalized or die from flu-related causes. People who work in close physical spaces with others who are infectious, such as in office cubicles, or travel on crowded public transportation, may be exposed to influenza viruses easily. So are those who sleep and live in tight quarters with individuals who may be infected, such as in shelters, nursing homes or college dormitories.

The CDC and its Advisory Committee on Immunization Practices (ACIP) recommend flu vaccination for the following groups:

• People 50 years and older

• People who live in nursing homes and other long-term care facilities that house those with long-term illnesses

• Adults and children six months* and older with chronic heart or lung conditions including asthma

• Adults and children six months* and older who needed regular medical care or were in a hospital during the previous year because of a metabolic disease (like diabetes), chronic kidney disease or weakened immune system (including immune system problems caused by medicines or by infection with HIV/AIDS)

• Children six months* to 18 years of age who are on long-term aspirin therapy. (Children given aspirin while they have influenza are at risk of Reye's syndrome.)

• Women who will be pregnant during the influenza season

• All children six* to 59 months of age

• People with any condition that can compromise respiratory function or the handling of respiratory secretions (that is, a condition that makes it hard to breathe or swallow, such as brain injury or disease, spinal cord injuries, seizure disorders or other nerve muscle disorders.)

It is also recommended that the following groups get vaccinated against influenza:

• Any person in close contact with someone in a high-risk group including

• Health care workers
• Household contacts and out-of-home caregivers of children six to 59 months
• Close contacts of people 65 years and older

A word of caution: If you are allergic to eggs, have ever had an allergic reaction to flu vaccine, have ever had Guillain-Barré syndrome, or have a current illness, consult your health care professional before receiving either vaccine. For more information, visit www.cdc.gov/flu.

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Signs and Symptoms of Flu

How do you know if you have the flu (influenza) or just a cold? Both affect your respiratory system and have similar symptoms. However, there are significant differences in the severity of each illness and their potential to cause serious complications or death:

A cold creeps up on you, little by little. It might start with sneezing, then move on to a sore throat or achy muscles. You might not feel great, but-armed with enough tissues-you can still pursue most daily activities.

The flu strikes quickly, often with debilitating exhaustion. Flu usually makes you too sick and weak to go to work, school or even to leave your bed.

With the flu, you'll often have a high fever (102-104°F) that may last as long as four days, an intense headache, strong aches and pains, overall weakness and a serious dry cough. In addition, you could suffer chills, a runny or stuffy nose, and eye pain. And, after most flu symptoms have passed, fatigue can still linger. When you have a cold, you rarely have a fever or headache and fatigue is mild. Sneezing, a stuffed nose and sore throat are common with a cold, but less so with the flu.

And the time frame is different for the two illnesses: A cold may last only a few days, but the flu can make you miserable for two weeks or more.

Although people talk about having a "stomach flu," adults don't have stomach-related symptoms with the disease. Stomach flu isn't influenza—it's a gastrointestinal disorder.

Flu is usually diagnosed based upon symptoms and a physical exam. If your symptoms fit those of other patients becoming ill during the time when flu is in your community, your doctor can presume that you have one of the current strains of flu.

Because flu symptoms are sometimes similar to those of viral illnesses such as respiratory syncytial virus (RSV, the most common cause of bronchiolitis and pneumonia among infants and children under one year of age) and parainfluenza, as well as bacterial conditions such as bronchitis and pneumonia, you may receive more sophisticated diagnostic testing if needed. Lab tests based on viral swabs of your nasal passages or throat, or blood tests, can confirm whether you have the flu.

Annual vaccinations reduce or prevent your risk of getting the flu. As of yet, there are no effective vaccines for RSV or parainfluenza, although research continues.

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Flu Past…and Future

You may have heard from older relatives, or learned in history books, about the catastrophic 1918 influenza epidemic known as the "Spanish flu."

It was the fastest-moving, most lethal influenza outbreak in recorded history, resulting in at least 500,000 U.S. deaths and killing more than 50 million people worldwide. More than half of those who died were healthy people, aged 18 to 40.

Such disease outbreaks are called pandemics because they cover the entire world and affect many people. There were two other influenza pandemics in the 20th century, the Asian flu in 1957-1958 and the Hong Kong flu in 1968-1969. Together, they left at least 100,000 dead in the U.S.

Although modern flu vaccines and antiviral medications better protect public health, an average of about 36,000 people still die from flu-related causes in the U.S. every year. That's the result of an average flu season, not a pandemic. Worldwide, the fatality rate may be 20 times higher or more.

Experts are concerned that new flu strains, appearing in bird and animal populations, may threaten humans with a new pandemic. Some even consider such an event inevitable, fueled by a growing world population, increased foreign travel, and immunization levels that are still low among many people, despite flu being a vaccine-preventable disease.

How can each of us help lower the incidence and risks of flu outbreaks and pandemics in the future?

• Get a flu vaccination every fall, particularly if you are high risk for suffering flu complications. Remember, if you are allergic to eggs, have ever had an allergic reaction to flu vaccine, have ever had Guillain-Barré Syndrome, or have a current illness, you need to consult your health care professional before receiving a flu vaccination.

• Urge your relatives, friends and co-workers to get the vaccine every year.

• Be sure to vaccinate children over six months to five years of age in your family as well as adults.

• When you hear a flu myth being repeated as if it's a fact, set the record straight.

• Stop the spread of flu viruses and other infectious germs:

• Frequently wash your hands with soap and warm water, or use an alcohol-based hand cleaner.

• If you cough or sneeze, use a tissue to cover your mouth and nose

• When you don't have a tissue, cough or sneeze into your upper sleeve—not into your hands.

• Throw used tissues into the trash

• Wash hands after coughing, sneezing or blowing your nose.

• Avoid touching your eyes, nose or mouth (this reduces the chance that infection will enter your body).

• Stay home when you're sick.

• Avoid close contact with sick people when possible.

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Create Date: 10/14/05
Date Last Updated: 8/14/06